1. 利用mininet创建如下拓扑，要求拓扑支持OpenFlow 1.3协议，主机名、交换机名以及端口对应正确，请给出拓扑Mininet执行结果，展示端口连接情况
端口连接情况
2. 直接在Open vSwitch下发流表，用vlan得到下列虚拟网段，请逐条说明所下发的流表含义
S1:
sudo ovs-ofctl add-flow -O OpenFlow13 s1 in_port=1,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:4
sudo ovs-ofctl add-flow -O OpenFlow13 s1 in_port=2,actions=push_vlan:0x8100,set_field:4098-\>vlan_vid,output:4
sudo ovs-ofctl add-flow -O OpenFlow13 s1 in_port=3,actions=push_vlan:0x8100,set_field:4099-\>vlan_vid,output:4
//将三台主机各设在一个vlan网络内（独立的vid），s1的数据包打上vlan tag从端口4向s2转发
sudo ovs-ofctl add-flow s1 in_port=4,dl_vlan=1,actions=strip_vlan,output:1
sudo ovs-ofctl add-flow s1 in_port=4,dl_vlan=2,actions=strip_vlan,output:2
sudo ovs-ofctl add-flow s1 in_port=4,dl_vlan=3,actions=strip_vlan,output:3
//接受从s2传来的数据包，去除vlan tag，分别根据dl_vlan（数据包原始的 VLAN ID）传送给同一vlan网络内的主机
S2:
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:4
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:4
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=3,actions=push_vlan:0x8100,set_field:4098-\>vlan_vid,output:4
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=0,actions=pop_vlan,output:1
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=1,actions=pop_vlan,output:2
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=2,actions=pop_vlan,output:3
3. 直接在Open vSwitch查看流表，提交OVS命令执行结果
S1：
S2:
4. 提交主机连通性测试结果，验证流表的有效性
5. 利用Wireshark抓包，分析验证特定报文
